| 1. |
- Talyzin, Alexandr, et al.
(författare)
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Reaction of hydrogen gas with C60 at elevated pressure and temperature: Hydrogenation and cage fragmentation.
- 2006
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 110:27, s. 8528-34
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Tidskriftsartikel (refereegranskat)abstract
- Products of the reaction of C60 with H2 gas have been monitored by high-resolution atmospheric pressurephotoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS), X-raydiffraction, and IR spectroscopy as a function of hydrogenation period. Samples were synthesized at 673 Kand 120 bar hydrogen pressure for hydrogenation periods between 300 and 5000 min, resulting in the formationof hydrofullerene mixtures with hydrogen content ranging from 1.6 to 5.3 wt %. Highly reduced C60Hx (x >36-40) and products of their fragmentation were identified in these samples by APPI FT-ICR MS. A sharpchange in structure was observed for samples with at least 5.0 wt % of hydrogen. Low-mass (300-500 Da)hydrogenation products not observed by prior field desorption (FD) FT-ICR MS were detected by APPIFT-ICR MS and their elemental compositions obtained for the first time. Synthetic and analytical fragmentationpathways are discussed.
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| 2. |
- Amirjani, M. R., et al.
(författare)
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Protochlorophyllide and POR development in dark-grown plants with different proportions of short-wave length and long-wavelength protochlorophyllide spectral forms
- 2006
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 128:4, s. 751-762
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Tidskriftsartikel (refereegranskat)abstract
- The effect of leaf developmental age on the protochlorophyllide (Pchlide) spectral forms and the expression of messenger RNA (mRNA) encoding NADPH-protochlorophyllide oxidoreductase (POR) were investigated. Four plant species, maize, wheat, pea and the lip 1 mutant of pea, known to have different composition of the spectral forms of Pchlide, were used. In very young plants short-wavelength Pchlide with a fluorescence emission at 631 nm was dominating. Long-wavelength Pchlide fluorescing mainly around 655 nm increased during development, which led to a relative decrease of the short-wavelength forms. During ageing of the leaves, the short-wavelength forms slightly increased again. The different proportions of short- and long-wavelength Pchlide spectral forms were, however, found to vary with the developmental stage in a species specific pattern. The steady-state level of POR mRNA and the amount of the POR protein were similar in species dominated by short-wavelength forms and in species dominated with long-wavelength forms. Even if POR is necessary for the formation of the long-wavelength Pchlide form it is not the only limiting factor for formation of long-wavelength Pchlide forms in mature plants.
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| 3. |
- Eneyskaya, Elena V., et al.
(författare)
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Transglycosylating and hydrolytic activities of the beta-mannosidase from Trichoderma reesei
- 2009
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Ingår i: Biochimie. - : Elsevier BV. - 0300-9084 .- 1638-6183. ; 91:5, s. 632-638
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Tidskriftsartikel (refereegranskat)abstract
- A purified beta-mannosidase (EC 3.2.1.25) from the fungus Trichoderma reesei has been identified as a member of glycoside hydrolase family 2 through mass spectrometry analysis of tryptic peptides. In addition to hydrolysis, the enzyme catalyzes substrate transglycosylation with p-nitrophenyl beta-mannopyranoside. Structures of the major and minor products of this reaction were identified by NMR analysis as p-nitrophenyl mannobiosides and p-nitrophenyl mannotriosides containing beta-(1 -> 4) and beta-(1 -> 3) linkages. The rate of donor substrate hydrolysis increased in presence of acetonitrile and dimethylformamide, while transglycosylation was weakly suppressed by these organic solvents. Differential ultraviolet spectra of the protein indicate that a rearrangement of the hydrophobic environment of the active site following the addition of the organic solvents may be responsible for this hydrolytic activation.
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| 4. |
- Kristensson, E, et al.
(författare)
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Acute psychological stress raises plasma ghrelin in the rat.
- 2006
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Ingår i: Regulatory Peptides. - : Elsevier BV. - 0167-0115 .- 1873-1686. ; 134:2-3, s. 114-117
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin is produced by the A-like cells of the stomach and mobilized by food deprivation. It was reported recently that acute psychological stress increases ghrelin gene expression in rat oxyntic mucosa. The aim of this study was to examine the effect of such stress on circulating ghrelin levels. To this end, we measured plasma ghrelin in Wistar Kyoto (WKY) rats (a high-anxiety strain) and Sprague–Dawley (SPD) rats (a low-anxiety strain), exposed to water avoidance stress for 60 min. Blood was collected before and after the stress. Acute stress increased the plasma ACTH concentration not, vert, similar5-fold (p < 0.01) in both strains of rats, while plasma ghrelin increased by 85% (p < 0.01) in the SPD rats and by 40% (p < 0.001) in the WKY rats. Ghrelin levels after acute stress were higher (p < 0.05) in the SPD rats than in the WKY rats. Sham stress did not affect plasma ghrelin. We conclude that acute psychological stress mobilizes ghrelin and that the SPD rats respond with a higher plasma ghrelin concentration than the WKY rats.
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| 5. |
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| 6. |
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| 7. |
- Schmidt, P.T., et al.
(författare)
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Circulating ghrelin levels after food intake during different phases of the migrating motor complex in man.
- 2006
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 36:7, s. 503-509
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Tidskriftsartikel (refereegranskat)abstract
- Background The timing of the migrating motor complexes (MMC) at food intake may influence gastric emptying and release of regulatory hormones. This report studies the relationships between phases I (motor quiescence) and II (intermediate frequency contractions) of MMC and prandial gut hormone response. Materials and methods Seven fasting volunteers ingested a meal during phase I or II of MMC verified by manometry, using paracetamol as a marker for gastric emptying. Blood was sampled before, during and 210 min after food intake for analysis of ghrelin, motilin, insulin and paracetamol. Results The basal level of ghrelin during phase I was 127·5 ± 25·4 pmol L-1 and during phase II was 132·4 ± 24·8 pmol L-1. After food intake during phase I, ghrelin fell to 77·2 ± 10 pmol L-1; in phase II it fell to 82·7 ± 17·8 pmol L-1 within 60 min and returned to baseline levels after 120 min. Baseline levels of motilin were 16 ± 2 pmol L-1 and 18 ± 3 pmol L-1 during phases I and II, respectively. After food, motilin decreased to 8·5 ± 0·7 pmol L-1 and 8·7 ± 1·0 pmol L-1 within 60 min and returned to baseline after 90 min. Insulin levels in phases I and II were 8·1 ± 1·2 mU L-1 and 8·6 ± 0·7 mU L-1, respectively, reaching 138·9 ± 35·6 mU L-1 and 167·4 ± 30·0 mU L-1 at 45 min postprandially. Conclusions The nutritional status of the gastrointestinal tract at food intake had only a limited impact on plasma ghrelin. After food intake, plasma ghrelin drops, similar to motilin, and resumes preprandial levels within 120 min.
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| 8. |
- Sundqvist, J. O., et al.
(författare)
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MgI emission lines at 12 and 18 mu m in K giants
- 2008
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 486:3, s. 985-993
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Tidskriftsartikel (refereegranskat)abstract
- Context. The solar mid-infrared metallic emission lines have already been observed and analyzed well, and the formation scenario of the Mg I 12 mu m lines has been known for more than a decade. Detections of stellar emission at 12 mu m have, however, been limited to Mg I in very few objects. Previous modeling attempts have been made only for Procyon and two cool evolved stars, with unsatisfactory results for the latter. This prevents the lines' long predicted usage as probes of stellar magnetic fields. Aims. We want to explain our observed Mg I emission lines at 12 mu m in the K giants Pollux, Arcturus, and Aldebaran and at 18 mu m in Pollux and Arcturus. We discuss our modeling of these lines and particularly how various aspects of the model atom affect the emergent line profiles. Methods. High-resolution observational spectra were obtained using TEXES at Gemini North and the IRTF. To produce synthetic line spectra, we employed standard one-dimensional, plane-parallel, non-LTE modeling for trace elements in cool stellar atmospheres. We computed model atmospheres with the MARCS code, applied a comprehensive magnesium model atom, and used the radiative transfer code MULTI to solve for the magnesium occupation numbers in statistical equilibrium. Results. The Mg I emission lines at 12 mu m in the K giants are stronger than in the dwarfs observed so far. We present the first observed stellar emission lines from Mg I at 18 mu m and from Al I, Si I, and presumably Ca I at 12 mu m. We successfully reproduce the observed Mg I emission lines simultaneously in the giants and in the Sun, but show how the computed line profiles depend critically on atomic data input and how the inclusion of energy levels with n > ;= 10 and collisions with neutral hydrogen are necessary to obtain reasonable fits.
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| 9. |
- Talyzin, Alexander V., et al.
(författare)
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Composition of hydrofullerene mixtures produced by C60 reaction with hydrogen gas revealed by high-resolution mass spectrometry.
- 2005
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 109:26, s. 12742-12747
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Tidskriftsartikel (refereegranskat)abstract
- Complex solid hydrofulleride mixtures were synthesized by prolonged hydrogenation of C60 at 120 bar hydrogen pressure, 673 K temperature, and different reaction periods. The high degree of hydrogenation was confirmed by infrared spectroscopy and X-ray diffraction. The identity of hydrogenation products was determined by high-resolution field desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry. Despite partial gas-phase fragmentation of hydrofullerene ions during mass analysis, the data suggest that the synthesized mixtures consist of mostly C58-60Hx hydrofullerenes. Increasing the duration of hydrogenation results in synthesis of C59Hx and C58Hx as major products. Possible hydrofullerene fragmentation pathways during both material synthesis and mass spectrometric analysis are discussed. Gas-phase fragmentation in the mass spectrometer arises from hydrofullerene ions C60Hx+ with x > 40 and C59H44+ with drastically decreased molecular stability relative to the known C60H36.
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| 10. |
- Amirjani, M.R., et al.
(författare)
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Red region excitation spectra of protochlorophyllide in dark-grown leaves from plant species with different proportions of its spectral forms
- 2005
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Ingår i: Photosynthetica. - : Institute of Experimental Botany. - 0300-3604 .- 1573-9058. ; 44:1, s. 83-92
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Tidskriftsartikel (refereegranskat)abstract
- Etiolated leaves of three different species, maize, wheat, and pea, as well as a pea mutant (lip1) were used to compare the excitation spectra of protochlorophyllide (Pchlide) in the red region. The species used have different composition of short-wavelength and long-wavelength Pchlide forms. The relation between different forms was furthermore changed through incubating the leaves in 5-aminolevulinic acid (ALA), which caused an accumulation of short-wavelength Pchlide forms, as shown by changes in absorption and fluorescence spectra. This is the first time a comprehensive comparison is made between excitation spectra from different species covering an emission wavelength range of 675750 nm using fluorescence equipment with electronic compensation for the variations in excitation irradiance. The different forms of Pchlide having excitations peaks at 628, 632, 637, 650, and 672 nm could be best measured at 675, 700, 710, 725, and 750 nm, respectively. Measuring emission at wavelengths between 675 710 nm gave an exaggeration of the short-wavelength forms and measuring at longer wavelengths gave for the pea leaves an exaggeration of the 672 nm peak. In general, an energy transfer from short-wavelength Pchlide forms to long-wavelength Pchlide forms occurred, but such an energy transfer sometimes seemed to be limited as a result of a discrete location of the Pchlide spectral forms. The excitation spectra resembling the absorption spectrum most were measured at an emission wavelength of 740 nm. Measuring the excitation at 710 nm gave higher intensity of the spectra but the short-wavelength forms were accentuated.
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| 11. |
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| 12. |
- Borglund, Erik A.M, et al.
(författare)
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The role of EDM in information management within SME’s
- 2007
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Ingår i: The Second International Conference on Digital Information Management (ICDIM'07). ; , s. 31-36
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Konferensbidrag (refereegranskat)abstract
- Electronic document management (EDM) is a new form of information management. EDM are described to have certain business values in organizations, but no researches have been found about EDM and Small and Medium sized Enterprises (SME). In this paper we present an ongoing investigation in two SMEs guided by the following research questions: How are electronic documents used in the SMEs? and What are the business needs of the SMEs, and how do they correspond with stated EDM business values?. The study was carried out as two qualitative case studies in two SMEs in the north of Sweden. The results show that the business need for an SME corresponds with the business values of EDM. Yet is management of electronic document too dependent on individuals competence, very complex when many systems are involved, and the context where the document is created is not preserved. There is also an emergent need for an organizationally specific classification schema to enable information sharing between systems.
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| 13. |
- Cato, Ingemar, et al.
(författare)
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DIOXINS AND OTHER POPS IN THE BALTIC SEA – TRENDS AND CURRENT
- 2009
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Ingår i: 29th International Symposium on Halogenated Persistent Organic Pollutants (Dioxin 2009) in Bejing, China, August 25-30, 2009.
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Konferensbidrag (refereegranskat)abstract
- This paper summarizes a project that was initiated by the Swedish Environmental Protection Agency (EPA) in 2006. It involved several field studies and fate model calculations with the aim to better understand the present contamination situation of dioxins and other persistent organic pollutants (POPs) in the Baltic Sea region. Atmospheric inputs were found to be the dominant external source for all of the selected POPs (dioxins, PCBs and HCB). The model also predicted a significant decline of POP-levels in Baltic surface water if atmospheric concentrations are reduced. This issue is highly prioritized by the Swedish EPA since TEQ-levels of fatty fish exceed maximum residue limits set by the EU. Dioxin source regions were identified by air measurements and analysis of air mass origin. It was found that air that had passed over the European continent contained the highest concentrations, and the congener composition indicated that several major sources types may exist. This research has high relevance for the Swedish EPA, and continued efforts for resolving the dioxin issue of the Baltic Sea will follow.
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| 14. |
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| 15. |
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| 16. |
- Eriksson, Ola, et al.
(författare)
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Municipal Solid Waste Management from a Systems Perspective
- 2005
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 13:3, s. 241-252
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Tidskriftsartikel (refereegranskat)abstract
- Different waste treatment options for municipal solid waste have been studied in a systems analysis. Different combinations of incineration, materials recycling of separated plastic and cardboard containers, and biological treatment (anaerobic digestion and composting) of biodegradable waste, were studied and compared to landfilling. The evaluation covered use of energy resources, environmental impact and financial and environmental costs. In the study, a calculation model ( ) based on methodology from life cycle assessment (LCA) was used. Case studies were performed in three Swedish municipalities: Uppsala, Stockholm, and Älvdalen. The study shows that reduced landfilling in favour of increased recycling of energy and materials lead to lower environmental impact, lower consumption of energy resources, and lower economic costs. Landfilling of energy-rich waste should be avoided as far as possible, partly because of the negative environmental impacts from landfilling, but mainly because of the low recovery of resources when landfilling. Differences between materials recycling, nutrient recycling and incineration are small but in general recycling of plastic is somewhat better than incineration and biological treatment somewhat worse. When planning waste management, it is important to know that the choice of waste treatment method affects processes outside the waste management system, such as generation of district heating, electricity, vehicle fuel, plastic, cardboard, and fertiliser.
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| 17. |
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| 18. |
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| 19. |
- Gurevich, A.M., et al.
(författare)
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Low temperature heat capacity of fullerite C60 doped with nitrogen
- 2006
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 32:10, s. 967-969
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Tidskriftsartikel (refereegranskat)abstract
- The heat capacity C-m of polycrystalline fullerite C-60 doped with nitrogen is measured in the temperature interval 2-13 K. The contributions to the heat capacity from translational lattice vibrations (Debyc contribution), from orientational vibrations of the C-60 molecules (Einstein contribution), and from the motion of the N-2 molecules in the octahedral cavities of the C-60 lattice are estimated. However, no indications of the first-order phase transformation detected earlier in a dilatometric investigation of the N-2-C-60 orientational glass are found (beyond the experimental error limits). A possible explanation for this fact is proposed.
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| 20. |
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| 21. |
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| 22. |
- Prokhvatilov, A.I., et al.
(författare)
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Hysteretic phenomena in Xe-doped C60 from X-ray diffraction
- 2005
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:5, s. 585-589
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Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline fullerite C60 intercalated with Xe atoms at 575 K and a pressure of 200 MPa was studied by powder x-ray diffraction. The integrated intensities of a few brighter reflections have been utilized to evaluate the occupancy of the octahedral interstitial sites in C60 crystals, which turned out to be (34±4)%, and in good agreement with another independent estimate. It is found that reflections of the (h00) type become observable in Xe-doped C60. The presence of xenon in the octahedral sites affects both the orientational phase transition as well as the glassification process, decreasing both characteristic temperatures as well as smearing the phase transition over a greater temperature range. Considerable hysteretic phenomena have been observed close to the phase transition and the glassification temperature. The signs of the two hysteresis loops are opposite. There is reliable evidence that at the lowest temperatures studied the thermal expansion of the doped crystal is negative under cool-down.
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| 23. |
- Stadnichuk, I. N., et al.
(författare)
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Identification of spectral forms of protochlorophyllide in the region 670-730 nm
- 2005
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Ingår i: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 4:2, s. 230-238
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Tidskriftsartikel (refereegranskat)abstract
- Dark-grown leaves of three different species, maize, wheat, pea and a pea mutant (lip1) have been used to study protochlorophyllide (Pchlide) spectral forms. As a comparison also pea epicotyls were used. Different native forms of Pchlide were identified using the variation in the spectral properties of the plant material and the second derivatives of the 77 K fluorescence excitation and emission spectra. The spectral forms were further characterised by Gaussian deconvolution. In addition to short-wavelength and long-wavelength forms the area between 660 and 730 nm was shown to contain, together with some vibrational bands,five far-red Pchlide forms. They had pairs of excitation and emission peaks at 658 and 666 nm, 668 and 680 nm, 677 and 690 nm, 686 and 698 as well as 696 and 728 nm, respectively. The presence of several far-red Pchlide forms in dark-grown leaves gave evidence for additional aggregated states of Pchlide under native conditions.
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| 24. |
- Sundqvist, Kristina, et al.
(författare)
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Concentrations and Congener Patterns of PCDD/FS in Surface Sediment, Settling Particulate Matter, Water and Fish From the South Bothnian Sea, Sweden
- 2007
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Ingår i: Organohalogen Compounds. ; 69, s. 247-50
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Tidskriftsartikel (refereegranskat)abstract
- This study focused on PCDD/F contamination along the Swedish coast of the southern Bothnian Sea, a heavily polluted area of the Baltic Sea. Data from earlier studies of surface sediment, perch, viviparous blenny and herring were analyzed together with new data for settling particulate matter (SPM) and sea water. PCDD/F pollution in surface sediment and SPM in the southern Bothnian Sea were similar both in respect to pattern and levels. The highest levels were 170 000 and 33 000 pg/g TOC in sediment and SPM respectively, and the congener pattern was dominated by OCDD, OCDF and 1,2,3,4,6,7,8-HpCDF. The dissolved concentrations in water were estimated by analysis of passive samplers of low density polyethylene (LDPE) type. The water pollution pattern was extremely different and showed complete domination of 2,3,7,8-TCDF. The fish showed species specific differences in the fractions of the two dominating congeners, 2,3,7,8-TCDF and 2,3,4,7,8-PeCDF. All species did, however, show an increase in the fraction 2,3,4,7,8-PeCDF as compared to the pattern in passive water samplers.
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| 25. |
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| 26. |
- Talyzin, Alexandr, et al.
(författare)
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Hydrogenation of C60 at 2 GPa Pressure and High Temperature.
- 2006
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Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104. ; 325:2-3, s. 445-451
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogenation of C60 at 2 GPa and 723–823 K was performed with thermal decomposition of LiAlH4 as a hydrogen source. Analysisof hydrogenation products showed that the method can produce not only C60H36, but also hydrofullerides C60Hx with 44 < x < 52.Unlike other hydrogenation methods in which pristine C60 reacts with hydrogen, the high pressure/high temperature conditions resultfirst in C60 polymerization into a tetragonal phase which later reacts with hydrogen. It is suggested that hydrogen first attacks intermolecularcarbon–carbon bonds, resulting in complete depolymerization of C60 at a later stage of the hydrogenation process. This modelsuggests the possibility to select starting points for hydrogenation by choosing specific polymeric structures of C60. Hydrogenated polymericC60 was identified as an intermediate reaction product. Characterization of highly reduced material was performed by Raman andIR spectroscopy, X-ray diffraction, and atmospheric pressure photoionization Fourier transform ion cyclotron resonance massspectrometry.
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| 27. |
- Talyzin, Alexandr, et al.
(författare)
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Synthesis of C59Hx and C58Hx fullerenes stabilized by hydrogen
- 2005
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Ingår i: Journal of Physical Chemistry B Letters. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 109:12, s. 5403-5
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged hydrogenation of C60 molecules by reaction with H2 at elevated temperature and pressure resultsin fragmentation and collapse of the fullerene cage structure. However, fragments can be preserved byimmediate termination of dangling bonds by hydrogen. Here we demonstrate that not only fullerene fragmentsbut also hydrogenated fragmented fullerenes (e.g., C58H40 and C59H40) can be synthesized in bulk amount byhigh-temperature hydrogenation of C60. We confirm successful synthesis of these species by matrix-assistedlaser desorption ionization time-of-flight mass spectrometry and complete speciation of the resultant complexfullerene mixtures by high-resolution field desorption/ionization Fourier transform ion cyclotron resonancemass spectrometry.
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| 28. |
- Yao, Mingguang, et al.
(författare)
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Synthesis and growth mechanism of differently shaped C60 nano/microcrystals produced by evaporation of various aromatic C60 solutions
- 2009
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Ingår i: Carbon. - Amsterdam : Elsevier. - 0008-6223 .- 1873-3891. ; 47:4, s. 1181-1188
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed study of the synthesis of C60 nano- and microrods as well as crystals with normal shapes by the evaporation of C60 solutions based on different aromatic solvents. C60 nano- and microrods are grown with high yield by vaporizing C60 solutions in meta-isomers of aromatic solvents on different substrates while para-isomers give a different type of growth leading to highly crystalline two- and three-dimensional nano- and microcrystals with fcc structure. The role of solvent properties was investigated by using positional isomers containing different halogen radicals. The as-grown crystal rods formhexagonal structures but transform into fcc structure on annealing in vacuum. IR and EDX analysis indicate that solvents remain in the hexagonal nano- and microrods, while it is hard to detect any trace of solvents in the two- or three-dimensional nano- and microcrystals. Furthermore, we present direct proof of the nucleation-growth mechanism for C60 rods. By the vaporization method, the solubility of C60 in the studied halogen aromatic solvents is found to correlate with the diameter distribution of the C60 rods and we suggest that the chemical affinity of the aromatic solvent molecules to C60 may determine its ability to force C60 to form rod-shaped crystals.
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| 29. |
- Yao, Mingguang, et al.
(författare)
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Synthesis of single-wall carbon nanotubes and long nanotube ribbons with Ho/Ni as catalyst by arc discharge
- 2005
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 43:14, s. 2894-2901
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Tidskriftsartikel (refereegranskat)abstract
- The effect of a new bimetallic catalyst Ho/Ni for synthesis of single-walled carbon nanotubes (SWNTs) by arc discharge has been studied. Long ribbons consisting of roughly-aligned SWNT bundles were obtained by a modified arc discharge apparatus. Ribbon lengths can reach as much as 20 cm. Both elements Ho and Ni play important roles in the synthesis of SWNTs with high yield and purity. Changes in the Ho and Ni concentration in the catalyst hardly affect the diameter distribution of SWNTs, but the yield and purity of SWNTs are very sensitive to the concentration. An optimal range of Ho/Ni compositions for synthesis of SWNTs with relatively high purity and yield is given.
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